The connector with which the present invention has its most advantageous utilization consists of plug and receptacle parts which can be releasably joined to one another to effect electrical connection between cable wires through internal pin and socket contacts. An ever increasing requirement is that the connector and its wires leading thereto be protected against pollution by external electromagnetic fields. The cable end of the connector parts are readily accessible to such external fields and special means are used in order to eliminate, to the extent possible, ingress of these fields into the cable end of the connector part. A well accepted manner of doing this is to use a backshell consisting of a metal tube interconnected to the connector part by clamping thereon through the use of an electromagnetic forming technique sometimes referred to as "magneforming" which effectively seals off even minute openings or spaces between the backshell and the connector part thereby protecting the enclosed electrical parts from external ambient fields.
U.S. Pat. No. 4,579,415, Cable Shield Grounding Apparatus by M. K. Van Brunt and J. J. Hager discloses such a clamping of a tubular backshell onto a connector part by the use of an electromagnetic forming technique. It is additionally a requirement of this patent application that the backshell and connector part be protected against dust, dirt and moisture from the environment and the technique described therein and which is frequently employed at the present time, is to provide an O-ring located within a groove in the outside peripheral surface of the connector part which is compressed when the backshell is clamped thereon to effect environmental sealing.
There are many situations in which the physical size of a given connector part where the O-ring must be located is of restricted thickness and, therefore, cannot accommodate the required depth for an O-ring groove. Also, for most efficient production of an electromagnetically formed tubular metal backshell onto a mandrel, such as a connector part, it is important that the backshell and mandrel be held in alignment during magnetic forming. In the past, alignment has been accomplished by special holding fixtures and alignment tooling. The fixtures and tooling can be relatively complex and expensive when quality forming and repeatability are required.